This application claims the priority of German Application No. 100 12 517.4, filed Mar. 15, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process for designing flight controllers.
In modern controlled airplanes there exists the requirement to compensate for severe structural vibrations, especially with the use of ever softer airplane structures.
German Patent document DE 198 41 632.6 discloses a process to compensate for the structural vibrations of an airplane arising from turbulence and buffeting, where the structural vibrations are detected, according to a measuring method, by means of the rotational speeds that are determined by an inertial sensor system. The detected rotational speeds are fed to the flight control system, and control flap movements are produced, according to phase and amplitude, for the purpose of minimizing the phases and amplitudes of the excited vibrations. The design of flight control systems is known from the military specification MIL-A-8868B for the elastic airplane and from MIL-F-8785B for the rigid airplane, where the open circuit diagrams for phase delay and damping generally specify an amplitude margin of 6 dB and, independently thereof, a phase margin of at least +/xe2x88x9245 degrees.
The object of the invention is to provide a process for designing a flight controller that is suitable especially for soft airplane structures.
This problem is solved by a process for designing flight controllers, in which first for the rigid airplane and then for the elastic airplane the damping and the phase delay for each excitation frequency is determined. The flight controller is adapted in such a manner that the structural responses to each excitation frequency for both the rigid airplane and the elastic airplane in the open control circuit outside two design fields, applicable to the elastic airplane, are located around the instability points in the data field comprising damping and phase delay, whereby for the design of the elastic airplane between the phase delays of xe2x88x92270 degrees and xe2x88x92495 degrees, a damping exceeding xe2x88x926 dB is allowed. Other embodiments are described herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.